The present invention relates generally to a disposable absorbent garment and a process of making the same.
Disposable absorbent garments contemplated by the invention include disposable diapers, disposable pull-on garments, and the like. These garments are worn about the lower torso or waist of the user so as to receive and contain urine and other bodily wastes. Disposable diapers are particularly intended for use on infants who depend on a caretaker to fit the diaper. Typically, the infant is laid down while the caretaker places the garment around the waist region of the infant and then secures two ends on each side of the diaper together.
Disposable pull-on garments include training pants, pull-on diapers, disposable underwear, and adult incontinence garments. It is generally expected that the user of any one of these garments will be able to put on and take off the garment on his/her own. As for training pants, these garments are intended for use on a young child just before or about the time the child is ready to graduate from diapers to regular underpants (i.e., during toilet training). Training pants (and other disposable pull-on pants) have closed sides such that the user or care giver raises the garment about the user""s legs to put it on and slips the garment downward about the user""s legs to take it off. Thus, training pants (and other pull-on pants) are designed to be put on and taken off in the same manner by which regular underpants are put on and taken off. This feature is particularly advantageous in toilet training because it provides an early introduction to underpants and, more specifically, trains the child to wear regular underpants. Similarly, it is advantageous that the training pants fit and look very much like regular underpants so that the child is comfortable in making the transition from training pants to regular underpants.
The principal elements that typically make up the disposable absorbent garments described above are a liquid-permeable inner layer (or topsheet), a liquid-impermeable outer layer (or backsheet) and an absorbent core sandwiched between the inner and outer layers. Elastic members may also be incorporated into different parts of the garments. For example, elastic members may be positioned longitudinally along the diaper, generally outboard of the absorbent core to effect a seal around the buttocks, legs or both of the user. In addition, several elastic members (e.g., in the form of elongated elastic threads) may be positioned laterally throughout the waist region (including the side waist regions) of a disposable absorbent garment to allow the garment to stretch when it is put on and then during wear. In this way, the garment can stretch to accommodate variations in waist size and leg size of the user, while fitting snugly about the waist and legs and without sagging. One drawback, however, is that the elastic strands are visible on the outer surfaces of the garment and can interfere to some extent with decorative or instructional printing displayed on the outer surfaces of the garment.
Despite the increasing acceptance of disposable garments over the traditional cloth diapers, environmental concerns remain. A closely related issue is xe2x80x9csource reductionxe2x80x9d as it relates to conservation of resources. Accordingly, products which require fewer materials to accomplish the same functionality are particularly desirable.
Moreover, due to the high frequency of use and inherent xe2x80x9cdisposabilityxe2x80x9d of disposable garments, consumers are very sensitive to the price they pay for the garments. Therefore, it is desirable for manufacturers to provide a more cost-effective disposable absorbent garment.
It is also known to provide disposable garments with separate side waist regions in the form of elastic side panels such as those disclosed in U.S. Pat. No. 4,938,753. The elastic side panels described therein have side edges, which are attached to the outer edges of a central absorbent core assembly. The elastic side panels may be made from various elastomeric materials or combinations thereof and provide a more uniform fit generally more snug than side waist regions having elongated elastic strands. Moreover, the elastic side panels provide outer surfaces, which are more uniform than the outer surfaces on side waist regions having elongated elastic strands. However, the elastomeric material for the side panel does not typically provide for a smooth, even outer surface when the side panels are in either the relaxed state or the stretched state. Accordingly, the side panels are not particularly conducive to having decorative or instructional printing displayed thereon. In addition, the cost of producing separate side panel products is high due to the nature of the materials and the process difficulties of handing multiple web components. Again, the cost is critical to users of disposable garments due to their high rate of use. Furthermore, the separate side panel construction inherently relies on additional seams which detract from the product""s appearance, making the product look less like real underwear.
Alternatively, it is known to provide a unitary pair of training pants with elasticized ear flaps such as those disclosed in U.S. Pat. No. 5,246,433. The elasticized ear flaps are formed by sandwiching a relaxed elastomeric element between two material layers of the ear flaps, and adhesively attaching the material layers to the relaxed elastomeric element to form an elastic laminate. The design also calls for mechanically stretching the elastic laminate such that the material layers permanently deform. Although the side waist region according to this design generally provides a more uniform fit than a side waist region having elongated elastic strands, the outside surfaces of the side waist region are not conducive to having decorative or instructional print displayed thereon because the mechanically stretched material layers are uneven and cannot fully return to their original undistorted configuration. Other drawbacks of this and related designs include: 1) poor appearance due to deformation of materials, 2) limited range of stretch, and 3) loss of integrity of the inner and outer layers, weakening the product and forcing the use of higher strength and higher cost elastomers.
It is, therefore, one object of the invention to provide an improved disposable absorbent garment such as a diaper or adult incontinence garment, and an improved method of making such a garment and/or components of the garment.
Such a disposable absorbent garment is provided having a topsheet, a backsheet, and an absorbent core disposed between the topsheet and the backsheet. The topsheet, backsheet, and core together form a front region, a back region, and a crotch region disposed between the front region and the back region. To facilitate reference, the garment may be described as having a vertical longitudinal plane that extends substantially centrally through the front, back and crotch regions.
Preferably, each of the front and back regions includes a pair of ear portions, which extend in substantially opposite lateral directions with respect to the longitudinal plane. Each ear portion is a breathable, stretchable layer assembly. Preferably, this stretchable layer assembly includes a plurality of breathing or vent sites which are spaced from one another to present a staggered pattern of vent sites on the ear portions. At the vent sites, an outer material layer of the ear portion (e.g., an extension of the backsheet) is bonded with an inner material layer of the ear portion (e.g., an extension of the topsheet). As a result of a bonding process, such as ultrasonic bonding, vent sites are created which include a hole(s) or aperture(s) through the stretchable material layer (and through the inner material layer and the outer material layer) and through which air is passable.
A variation of the disposable absorbent garment is provided having a topsheet, a backsheet, and an absorbent core disposed between the topsheet and the backsheet. The topsheet, backsheet, and absorbent core form a front region, a back region, and a crotch region disposed between the front region and back regions. Further, each of the front and back regions includes a pair of ear portions extending in substantially opposite lateral directions. Each ear portion has a stretchable layer assembly of an outer material layer, an inner material layer, and a stretchable member or material layer secured therebetween. The outer material layer is an extension of the backsheet and extends laterally to form, at least partially, a side edge of the ear portion (i.e., side edge of the garment). Similarly, the inner material layer is an extension of the topsheet and extends laterally to also form, at least partially, a side edge of the ear portion. Accordingly, an ear portion may be formed that is seamless (i.e., along the outer and inner surfaces) as well as stretchable.
Preferably, the topsheet is a three-piece topsheet assembly consisting of a central section (including a portion generally disposed over the core) and a pair of side or outer sections which form or provide the inner material layers of two of the ear portions (e.g., for the two ear portions or the two right ear portions). Moreover, the garment may include a longitudinally-extending, preferably elasticized, leg cuff spaced in generally parallel relation from each lateral side of the core. The leg cuff may include an outer material, section or layer that is formed from the topsheet (e.g., topsheet side or outer section) and an inner material, section or layer that is substantially impervious.
Further yet, the stretchable material layer may be one that is extendible between a contracted configuration and an extended configuration and is preferably secured to the outer material layer when the stretchable material layer is disposed in the extended configuration. As a result, the outer material layer is subsequently contractible then extendible with the stretchable material layer (and, more particularly, its outer surface is returnable to a substantially smooth and planar configuration).
The garment employs relatively fewer number of materials and components than is typical of prior art garments and is relatively less expensive to produce. Such attributes are particularly important in products such as diapers and training pants which are consumed by users at a high rate. As compared to prior art products with side panels, the present invention provides a garment with stretchable ear portions or layers which are seamless and thus have a more desirable appearance which employ fewer components and relatively easy to construct. As a result, these garments are relatively less costly and more comfortable to wear. Further, the garment is relatively lighter than prior art garments, and thus more comfortable to wear.
Yet another variation of the disposable absorbent garment is one having a topsheet, a backsheet, and an absorbent core disposed between the topsheet and the backsheet. The topsheet, backsheet, and the absorbent core also form a front region, a back region, and a crotch region disposed between the front and back regions. Each of the front and back regions includes a pair of ear portions extending in substantially opposite lateral directions. The garment further includes a longitudinally extending leg cuff spaced, in generally parallel relation, from each lateral side of the core. The leg cuff has a first layer formed from a substantially impervious material (e.g., preferably a hydrophobic material such as a polymeric material) and a second layer formed from the topsheet. It is to be understood that the first and second layers of the leg cuff may also be referred to as cuff sections, cuff material or surface, cuff wall and like structure.
For purposes of the present descriptions of the invention, the term xe2x80x9cimperviousxe2x80x9d means impervious to liquid passage. Also, the term xe2x80x9cbreathable structurexe2x80x9d means a structure that substantially allows air to pass therethrough.
The garment may also include a pair of longitudinally extending leg cuffs, wherein each leg cuff is spaced from a lateral side of the core. Further yet, the garment includes a substantially impervious containment structure or barrier defined by the polymeric layer and a pair of substantially impervious sections (e.g. a polymeric side section), extending from one of the leg cuffs to sealingly engage the polymeric layer. Each leg cuff has an outer barrier layer and an inner barrier layer that is a portion of one of the substantially impervious sidewalls. Moreover, the containment structure forms a continuous and substantially impervious barrier (e.g., against core leakage) around the core (i.e., except above the core wherein the waste is received).
A method of forming a breathable, stretchable section of a disposable absorbent garment, such as a stretchable side panel or ear region, is also described in detail herein. The method includes steps of selecting a first material for a first material layer (e.g., a topsheet nonwoven material) and a second material (e.g. a backsheet nonwoven) for a second material layer, whereby the first and second material layers are bondable by an ultrasonic bonding process, and selecting an elastic material (e.g., an elastomer) for a stretchable material layer. The stretchable material layer is positioned between the first and second material layers to form a layer assembly, then one or more bond sites on the layer assembly are targeted for bonding one or more of the material layers together. The method then calls for securing the first, second, and stretchable layers together by ultrasonically bonding the first material layer with the second material layer at the one or more sites. Accordingly, an aperture is formed through the stretchable material and the first material layer and the second material layer bond through the aperture, such that the aperture provides a breathable passage therethrough. In a further variation, the targeting step includes longitudinally and laterally spacing the bond sites so as to create a staggered pattern of breathable bond sites on the stretchable section of the garment. This staggered pattern allows for maximum contracted (minimum relaxed) dimensions thus maximizing the fit range of the product.
A stretchable section is therefore produced that provides improved comfort and functionality, among other attributes. The method may be employed to form various sections of the garment including an ear portion or waist portion.
In one method according to the invention, a composite web structure is formed that is finishable to form a disposable absorbent garment. This method includes the steps of providing a core assembly and forming a topsheet assembly having a pair of longitudinally-extending, elasticized leg cuffs. The method further includes applying the topsheet assembly on the core assembly to create a first web structure assembly. Also, a backsheet assembly is formed that includes a backsheet material and this assembly is applied on the first web structure assembly to form a second web structure assembly. This second web structure assembly can then be cut at one or more locations to form the composite web structure.
Preferably, the step of forming a topsheet assembly includes the steps of: providing two webs of the topsheet material and two webs of elastic material to form two subsequent webs; providing a first web and a second web of the polymeric liner material, respectively; applying each web of elastic material onto one of the webs of topsheet material; and applying the first web of polymeric liner material onto one of the webs of topsheet material and the second web of polymeric liner material onto the other web of topsheet material. Each web of polymeric liner material is applied adjacent a web of the elastic material, and such that the subsequent folding step creates a leg cuff having one layer of the topsheet material, a second layer of the polymeric liner material, and elastic material there between.
Further, the step of forming a topsheet assembly may include providing a third web of a topsheet material and centrally applying the third web of topsheet material so as to engage each of the assemblies having elasticized leg cuffs to form a web of a topsheet assembly having a pair of topsheet side sections and a topsheet central section provided by topsheet material from the third web. The web of topsheet assembly is cut to form a discrete topsheet assembly, before the step of applying the topsheet assembly onto the first web structure. Further yet, the method may include the steps of providing a polymeric film material and applying the film material to the core assembly such that the first web structure includes a topsheet assembly above the core and polymeric film material beneath the core. Accordingly, the step of forming a topsheet assembly includes providing a pair of longitudinally-extending leg cuffs, each cuff having a cuff layer formed by a portion of a polymeric liner attached thereto. In one aspect of the inventive method, the free edge of each polymeric liner is applied so as to sealingly engage with the film material to create a substantially impervious containment structure about the core.
It should again be noted that the invention is adaptable to various types of disposable absorbent garments including, but not limited to, disposable diapers, training pants, adult incontinence garments and other pull-on garments.
These and other objects, features and advantages of the present invention will become apparent to those skilled in the art from the following detailed description and the drawings.